1. Field of the Invention
The present invention relates to a circuit-substrate laminated module composed of a first circuit substrate, a second circuit substrate created on the first circuit substrate, and a semiconductor chip created as a bare chip on the surface of the second circuit substrate. In addition, the present invention also relates to an electronic apparatus having a mother board implemented by a first circuit board that has a structure similar to the structure of the circuit-substrate laminated module.
2. Description of the Related Art
Efforts to reduce the size and thickness of an electronic product and an effort to make an electronic product capable of carrying out advanced functions and operating at high frequencies have made progress. In general, the circuit section of an electronic product is configured to employ a number of semiconductor integrated circuits and a number of circuit components on a printed wiring board referred to as a mother board. In the following description, a semiconductor integrated circuit is also referred to as an IC chip.
Miniaturization of the IC chips composing the electronic product and high-scale integration of the IC chips have also been progressing. For example, the so-called system LSI (Large Scale Integration) conversion, which is described below, has also made progress. In the past, an entire functional block was configured to employ a plurality of IC chips and a plurality of other circuit components on a printed wiring board. By the system LSI conversion, the entire functional block is implemented in a single semiconductor chip.
At the same time, the printed wiring board and components mounted on the board demand capabilities such as high frequency and high speed operations, to have smaller sizes, and integratable on a large scale.
To reduce the size and thickness of the electronic apparatus, it is necessary to mount a plurality of circuit devices including passive devices such as inductors, capacitors, and registers in a small area on the same substrate in addition to the IC chips. To mount such circuit devices in a small area on the same substrate in addition to the IC chips, it is practical to use an SiP (System in Package). The SiP is a package for implementing a plurality of IC chips and a plurality of such passive devices.
In addition, to further reduce the size and thickness of the electronic apparatus, technology development for creating a passive device on a printed wiring board have started. By virtue of this technology, it is possible to reduce the cost of an externally installed component that is difficult to incorporate in an IC chip in the present state of the art. In addition, such an externally installed component may be made in such a way that the component does not serve as a barrier to efforts to reduce the size and thickness of the entire substrate.
Typical examples of the externally installed component, which is difficult to incorporate in an IC chip in the present state of the art, include a capacitor having a large capacitance and an inductor having a large inductance (or a large L value). In particular, an inductor having a large L value is known to entail a number of electromagnetic interferences to circuit devices surrounding the inductor. For more information, the reader is advised to refer to documents such Japanese Patent Laid-Open No. 2006-60029 (hereinafter referred to as Patent Document 4).
If it is necessary to implement a plurality of passive circuit devices such as inductors each having a large L value so as to entail a number of electromagnetic interferences to other circuit devices surrounding the passive circuit device in a small area, the distances between the passive circuit devices become short. Thus, it is necessary to suppress interferences caused by mutual inductances of the passive circuit devices to serve as the interferences between the circuit devices. The interferences caused by mutual inductances to serve as the interferences between the passive circuit devices must be suppressed without regard to whether each of the passive circuit devices have been created by making use of a substrate lamination structure in a circuit substrate or each of the passive circuit devices have been created to serve as an individual component mounted on the surface of the circuit substrate.
As a technique for suppressing interferences between the circuit devices, there is a technique to devise surface implementation locations of chip inductors and laminated inductor components in a filter, an antenna sharing unit, and a communication apparatus. For more information on this technique, the reader is advised to refer to documents such Japanese Patent Laid-Open No. 2002-141707 (hereinafter referred to as Patent Document 1).
In addition, as a technique for implementing a shield of a high-frequency compound module making use of a multi-layer substrate, there is a technique to devise shield electrodes and through holes. For more information on this technique, the reader is advised to refer to documents such Japanese Patent Laid-Open No. 2007-151123 (hereinafter referred to as Patent Document 2).
Also, there is a technology to lay out inductors by avoiding the RF circuit of a signal transmitting/receiving section. For more information on this technology, the reader is advised to refer to documents such Japanese Patent Laid-Open No. 2009-59989 (hereinafter referred to as Patent Document 3).